Apparatus for producing hot gases



March 29, 1949.

A. MEYER APPARATUS FOR'PRODUCING HOT GASES Filed March 21, 1946 PatentedMar. 29, 1949 UNITED srAr 'arraaa'rus ron raon'uomo no'r cases AdolfMeyer, Kusnacht. Zurich, Switzerland, as-

signor to Aktlengesellschaft Brown, Boverl & Cie, Baden, Switzerland, ajoint-stock company Application March 21, 1946, Serial No. 656,127 I InSwitzerland March 28, 1945 40min torso-44) This invention relates to anovel apparatus for producing combustion gases at high pressure that areused for driving gas turbines and the like.

tion of driving gases for gas turbines has been to reduce solid fuelsuch as coal to gas in a gas producer and to burn this gas in thecombustion chamber associated with the turbine. In order to avoid theseseparate steps of first a reduction to gas and then a combustion. of theproduced gas, which requires both a gas producer and a combustionchamber, another method already proposed has been to subject solid.fuels in powdered or dust form to combustion in a shaftfumace under sucha pressure and with such an One method already proposed for the productially carried by it. By this means the intensive combustion, alreadycaused by the height of the air pressure employed, is still" furthersubstantially increased, so that the dimensions of 1 the furnace for agiven output may be still fur- .ther reduced.

This result is aided by the circumstance, that a with the high airpressure and the available presexcess of air that the products ofcombustion,

when leaving the shaft-fumace, have both the requisite pressurefordriving purposes, and also a high temperature favourable for theemciency of the turbine, but still safe for the blading. The combustionat the high pressure required for driving.the gas turbine has thisadvantage over the combustion at atmospheric pressure or only slightlyabove it, such as is usually employed for shaft-furnaces and boilers,that the combustion is far more intense and the dimensions of thefurnace become far smaller. Should the combustion be carried throughonly with the amount of excess air usually employed in boilers, thefinal temperature of the gases would be far too high for operating thegas turbine.

Now, in the method of producing hot gases,

more particularly for the operation .of gas turbines, by the combustionof solid fuels in powdered or dust form in a shaft-furnace under such apressure and with sue'h an excess Of air that the products of combustionhave both the requisite pressure for driving the turbine, driving theproducer and the like and also a high temperature which is neverthelesssafe for they sure drop the fuel layer may occupy a considerable height..With this mode of operation, however, it is not possible, owing to theconsiderable tractive force of the pressure air and its great quantity,to prevent some of the smaller parts of the fuel from being carried awaywith 'the products of combustion. For this reason there should be placedbeyond the burning layer an arrangement which separates out these solidresidues, in order that they will not pass into the gas turbine andthere cause erosion of the blades, pipes and'so forth. Hence, it is ofadvantage to use a portion of the compressed air which serves thepurpose of cooling the products of combustion for creating in the upperpart of the shaftfurnace a vortex which is adapted to throw out thesesolid residues. With this object in view, the portion of the compressedair intended for this purpose may beicaused to enter the separatingchamber through tangential nozzles. For this purpose one or moreseparators of known types may be used.

At the same time, and this is even more important, the combustion of therising combustible gas is first of all by means of the secondary air andthen with the excess air blown in tangentially and acting as coolingair, very favourably afiected. A very intense reduction of the combustion gases occurs because the fuel layer is .heated from abovebyradiation from the flame small through the combustion. The fuel willthus travel from above downwards.

An arrangement for carrying out the method according to the inventionthus consists, for in- With such a method at least a portion of the igreat excess of fresh air required-for bringing the final temperature ofthe combustion products down to a suitable value may be introduced intothe burning layer of fuel of suitable height in 1 particles becomesurrounded by air and are par-- stance, in a shaft-furnace with a feedopening for the solid fuel and an eduction pipe for the produced gasesin the upper part, a cone for spreading the fuel falling down on it andnozzles above and below the cone, of which the former are tangentiallydirected and serve the purpose of creating a vortex in the outflowinggas by means of the cooling air introduced through them, with the objectof throwing out slag and fuel, whilst the lower nozzles are intended inpart for the introduction of compressed air into the bed of the fire forloosening up and causing intensive combustion of the fuel layer and inpart for reintroducing the slag and fuel particles which are entrainedin air that is withdrawn from the upper part of the shaft furnace andreturned to the furnace below the fuel bed.

A suitable procedure has been found to be one in which the slag is madefluid and kept fluid by suitable regulation of the fire, as the slag canthus be removed from the pressure chamber in a far simpler manner thanis the case where solid slag is to be removed. By making certainadditions to the fuel, the melting temperature of the slag can beregulated.

The accompanying drawing shows by way example an arrangement forcarrying out the method according to the invention. The fuel such asfinely pulverized coal I which is fed in by a means of a feed regulatingdevice not shown, enters downwardly through a pipe 2 into theshaft-furnace 3 and spreads on the cone 4 flowing. down at the peripheryof the furnace into the bed 5 of the furnace in accordance with itsnatural slope. There air compressed by compressor 6 is introduced viapipes through nozzles 8 into the furnace bed from the bottom, the amountof air being such that the desired loosening of the layer of fuel and acorresponding intensity of combustion results. The combustion gasesescape through the layer of fuel at the periphery of the cone 4 andthrough holes 4a. in the latter, sweeping everywhere through freshlyarriving fuel. Through one or more tangent ally disposed nozzles 9 airfrom the output of compressor I 0 is also introduced, which acts assecondary air for the combustion of the gas and the excess portion ofwhich serves as cooling air, this air creating a waste gas vortex, thecentrifugal action of which throws out the solid residues of thecombustion and any particles carried along from the layer of fuel. As,owing to the peculiarity of the proposed mode of combustion, the solidresidues may still contain a considerable quantity of unburnt parts, itis of advantage to return these residues along with the conveying airwhich removes them from the separator back into the fire bed of theshaft-furnace. In order to reintroduce them, it is necessary somewhat toraise the pressure of the conveying air, as, in consequence of thelosses in the centrifugal separator, it has a lower pressure than thatprevailing in the combustion chamber. This raising of the pressure maybe affected by means of separate fans ll and by jet apparatus I2,operated by freshly arriving compressed air from compressor l3 whichsubsequently is used for the combustion. Thus, the

residues are drawn away by suction from furnace.

3 through holes [4 into chamber l5 and through openings I6 together withany gases which have been generated, and by means of the fans II, or thejet apparatus I2, the pipes l1, l8, l9, and the nozzles 20 are returnedto the furnace bed, where the combustible residues are completely burnt.This subjection of the unburnt pulverized fuel to suction may berepeated. Thegases, thus purifled, pass through the pipe 2! which isconcentric with the fuel inlet pipe 2 into the header chamber 22 andfrom there are conveyed through the pipe 23 for their ultimate use in agas turbine, a superheater, a steam, hot water or hot air producer.

The heavier slag particles settle downwardly 4 to the bottom of thefurnace 3 and are drawn off through pipe 24.

In order to assist the action of the fueldust separator, the fuelstreaming in from above may also be so guided that the combustionproducts are forced to sweep through a layer of fuel heating the latterand themselves being cooled down, when a great part of the solidresidues carried along by the products of combustion will be kept backin the layer of fuel. As, with this arrangement, light particles of fuelproduced by the crushing of the fuel may be carried away by the gasesand, on the other hand, the hot products of combustion may cause acertain degasification of the fresh incoming fuel, it is yet advisableto place after this kind of separator centrifugal separators or thelike, with the object of returning with conveying air the separated outfuel dust and any gases produced from the fuel back into the furnacebed.

In a furnace bed which as in this case is heated by radiation from theflame, it is natural that there will be a very intense reduction of thecombustion gases.

While in order to simplify illustration, separate blowers 6, I0 and I3have been shown for supplying pressure air, it will be obvious, ofcourse, that all of the pressure air could be delivered from a singleblower with suitable piping.

I claim:

1. In a furnace for producing hot gases, an upright casing, an inlet forpulverized fuel at the top of said casing, a gas eduction pipe at thetop of said casing, a perforated cone disposed transversely in saidcasing beneath said fuel inlet for spreading fuel falling upon it toform a layer of fuel underneath, nozzle means projecting through thewall of said furnace tangentially thereof above said cone, meansdelivering pressure air through said nozzle means to create a vortex inthe combustion gas to separate residue and unburnt fuel particlestherefrom, pipe means connecting the upper part of said furnace with thelower part thereof below said layer of fuel for reintroducing saidresidue and particles, an inlet to said furnace below said layer offuel, and means delivering pressure air to said inlet for loosening saidlayer of fuel and effecting intensive combustion thereof.

2. A furnace as defined in claim 1 and further including means insaid-pipe means for raising the pressure of the air flowingtherethrough.

3. A furnace as defined in claim 1 and further including a jet device insaid pipe means facing in the direction of air flow therethrough, andmeans delivering pressure air to said jet.

4. A furnace as defined in claim 1 wherein said cone is provided with aplurality of openings therethrough.

ADOLF MEYER.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name I Date 1,035,988 Miller Aug. 20, 19121,301 324 Schlatter Apr. 22, 1919 1,831 466 Schmidt Nov. 10, 1931 1,835332 Pinckard Dec. 8, 1931 1,875 545 Anderson Sept. 6, 1932 1 947 460Coutant Feb. 20, 1934 1,970 109 Shatton Aug. 14, 1934 2,315,336 KarrerMar. 30, 1943

